1. Field of the Invention
The preset invention relates to a text/image storage device that stores text/image information and transfers a text/image information file to a user terminal in response to a transfer request for the text/image information from the user terminal, an image reading device, and an image forming apparatus using the same. The text/image storage device of the present invention can be employed in document servers, printers, fax machines, document scanners, copy machines, and multifunction devices including such devices that store and use computerized text/document information such as image information taken by digital cameras, document image information from document scanners, text created with word processors, computer graphics and CAD drawings.
2. Description of the Related Art
[Patent document 1] Japanese Patent Laid-Open Publication No. 2000-89997
[Patent document 1] Japanese Patent Laid-Open Publication No. 2000-322338
[Patent document 3] Japanese Patent Laid-Open Publication No. 2002-213148
[Patent document 4] Japanese Patent Laid-Open Publication No. 2004-194278
Network systems that store image information from document scanners and documents created or edited by personal computers into document servers and use text/image information stored in the servers by downloading through networks are well known. These systems can be also used to store text/image information from document scanners and personal computers in document servers directly or through networks. Patent Document 1 discloses a network system of this type. In the meantime, network scanners that deliver images read by a document scanner to networks are widely used. Such a network scanner can store read images in a hard disk and can download them to terminals on a network. Patent Document 2 discloses a system using a scanner of this type.
In these years, it is becoming common to connect various types of image processing devices to a network such as a local area network (LAN). Users can store a large volume of image information in the image processing devices, send the stored image information to an information processing device on the network, and download information from the information processing device. In a network environment as described above, file formats commonly used for image information to be downloaded are multipage TIFF (Tagged Image File Format) and PDF (Portable Document Format). Files in these file formats can be read by an information processing device, so that users can see images contained in the files.
There are different types of data formats, such as binary data (binary image data) in which one bit is allocated to each pixel of an image, multilevel data (multilevel image data) in which plural bits are allocated to each pixel of an image, and vector data comprised of multilevel data (codes) representing types of shapes and characters, positions, and areas. Binary image data represent one-color binary images, which are generally called black-and-white images although they can also represent binary images in any one of, for example, yellow (Y), magenta (M), and cyan (C). The binary image data can be encoded in MH, MR, MMR, and JBIG formats. Among them, the MH format is commonly used because of its high compression rate. Multilevel image data, including gray scale images (monochrome halftone images such as black-and-white pictures) and color images (multicolor halftone images such as color pictures), are usually encoded in a JPEG format.
If text/image data are not compressed, binary data (binary image data) and multilevel data (multilevel image data and vector data) can be transferred as a TIFF file or a PDF file. For increasing transfer rate or lowering the amount of memory required, text/image information is converted in a file after being compressed and encoded. However, in many cases, if multilevel image data are compressed and transferred as a multipage TIFF file, personal computers (user terminals) cannot use the file.
According to Patent Document 3, if a file format is multipage TIFF, compressed binary image data are transferred as a file in TIFF-S (Tagged Image File Format Profile S), and compressed multilevel image data are transferred as a file in TIFF-C (Tagged Image File Format Profile C). However, TIFF-supporting software (e.g. Internet Explorer) installed as a standard application in Microsoft Windows™, which is the most widely used operating system for personal computers, supports compressed binary image data but not compressed multilevel image data. Because of this, the data format of text/image information in TIFF is usually binary image data (e.g. black-and-white image) compressed and encoded in an MH format. If compressed multilevel image data (e.g. color image) in TIFF are downloaded to a personal computer, the data cannot be read by the personal computer. That is, multilevel image data need to be converted into binary image data at the time of download so as to be used in TIFF.
Patent Document 4 discloses a multifunction copy machine having a color and monochrome copier function, a fax function, and an image file storing function. A HDD of the copy machine holds image data in various compression formats with various resolutions (dpi). When a transfer of the image data in a specified data format is ordered from a personal computer, by which image data are to be used, or from an operations panel of the multifunction copy machine, the multifunction copy machine converts the image data into the specified data format and transfers the data to the personal computer.